The success of research efforts to guide evidence-based care that is sensitive to the unique needs of Parkinsons disease (PD) patients rests on the effective enrollment of PD patients as research subjects. Yet the very problems caused by PD that warrant research are also the cause of ethical challenges to that research: progressive cognitive impairments. This project will understand the impact of cognitive as well as neuropsychiatric impairments on a patient's ability to make a research enrollment decision. This study will involve in-home, face-to-face interviews with 90 Parkinsons patients and 30 cognitively normal older adults. The interview will gather research consent capacity data using a standardized decisional capacity interview tool as well as cognitive assessments. We will examine the nature of the severity of capacity impairments in persons with Parkinsons disease and the patterns of those impairments to examine how capacity impairments vary as a function of overall cognitive impairment in Parkinsons disease and compare this performance to cognitively intact older adults. We will also examine the clinical significance of Parkinsons patient performance on the measures of the decisional abilities: understanding, appreciation, reasoning and choice. To achieve this, we will have expert raters judge whether the patient has sufficient capacity, which will allow us to examine how well a given ability score classifies a patient as capable of consent and how well measures of the clinical severity of Parkinson's disease associate with the risk of loss of capacity to consent. Finally, we will examine how personality traits affect both the capacity to consent and the decision whether to enroll in early phase research. In sum, the three aims of this project will show clinicians, investigators, patients and families how the cognitive and personality problems seen in persons with Parkinsons disease affect patients'ability to make ethically challenging decisions and the decisions that they make. PUBLIC HEALTH RELEVANCE: The success of research efforts to guide evidence-based care that is sensitive to the unique needs of Parkinsons disease (PD) patients rests on the effective enrollment of PD patients as research subjects. Yet the very problems caused by PD that warrant research are also the cause of ethical challenges to that research: progressive cognitive impairments. This project will understand the impact of cognitive as well as neuropsychiatric impairments on a patient's ability to make a research enrollment decision.